DE102008044733A1 - Active material-based joint-covering devices and methods of using the same - Google Patents

Abstract

A device for covering a joint between a first surface and a second surface comprises a joint-covering body fixedly attached to a selected one of the first surface and the second surface, or both, the joint-covering body comprising an active material, wherein the active material is formed is to switch between a first stiffness and a second stiffness upon receipt of an activation signal, the change permitting movement of a selected one of the first surface and the second surface, or both, such that the joint cover body deforms with the movement of the surface Maintain coverage of the joint.

Description

Cross reference to related Registrations

These Registration is a partial continuation and claims the benefit Non-Provisional U.S. Patent Application No. 11 / 848,488 on August 31, 2007, which is incorporated herein by reference in its entirety is included.

background

The The present disclosure relates generally to covering devices for Covering and / or filling the joints or seams between two surfaces of a vehicle and in particular Joint cover devices comprising active materials.

motor vehicles and other means of transport such. As aircraft, buses and trains have several movable (i.e., hinged, sliding or the like) Surfaces. In motor vehicles can such movable surfaces z. B. body panels such. As doors, hoods, luggage compartments, tailgates, Sunroofs, Glove compartments, Windows and the like include. Currently is between the movable area such as B. a sliding sunroof and a non-movable surface such z. B. the vehicle roof a joint (ie, a gap or an opening) available. This joint can partially limit the manufacturing tolerances for the sheets as well as columns are needed, which are required for operational Liche purposes. Currently impair the joints the vehicle aerodynamics as well as styling and aesthetics.

Quick Facts

Here in discloses a cover assembly based on an active material according to an exemplary Embodiment. In one embodiment comprises a device for covering a joint between a first surface and a second surface a body, which covers / covers the joint and stuck to a selected one from the first surface and the second surface or both, with the joint covering / covering body formed is to switch between a first shape and a second shape and wherein the change is a movement of a selected one of the first surface and the second surface or both, so that the joint body deformed and its coverage / coverage of / s Maintains gap / gap between the two surfaces; there it acts either directly or serves as an overlap for a reason covered hinge; and an active material in more functional Connection with the joint body, wherein the active material is adapted to receive upon receipt of a Activation signal a change to experience at least one property, with the change the at least one property is effective to the joint body of to convert the first form into the second form.

In a further embodiment comprises a device for covering a joint between a first surface and a second surface a joint cover / cover body, wherein the joint cover / cover body at least includes an active material that is firmly attached to a selected one of a first surface and a second surface or attached to both. The section of an active material the joint cover / cover body is formed, between a first stiffness and a second stiffness switch when activated or deactivated. The change between a first stiffness and a second stiffness leaves a Movement of a selected one from the first surface and the second surface or from both. The section of an active material of the joint body deformed yourself and hold the cover / cover the joint / gap of the joint body between the two surfaces upright, either acting directly as a hinge or as an overlap for a Hinge serves.

It is a method of covering a joint between a first one area and a second surface provided, wherein the method comprises a Fugenabdeckkörper between the first surface and the second surface is positioned, wherein the Fugenabdeckkörper comprises an active material, wherein the active material is adapted to receive an activation signal between a first stiffness and a second stiffness The change is a movement of a selected one of the first surface and the second surface or both, so that the joint cover body with the movement of the surface deformed to maintain the cover of the joint, wherein the active material with the activation signal is activated to yourself from the first stiffness to the second stiffness change and from a selected one from the first surface and the second surface or both from a first position to a second position move.

Brief description of the drawings

Under Referring now to the figures, the exemplary embodiments are and in which the same elements are designated the same, is:

1 a perspective view of a covering device based on an active material having (a) a first shape and (b) a second shape;

2 a perspective view of a covering device based on an active material having (a) a first stiffness and (b) a second stiffness;

3 a perspective view of yet another exemplary embodiment of a covering device based on an active material having (a) a first stiffness and (b) a second stiffness.

4 a perspective view of a covering device based on an active material, wherein the active material comprises portions which are embedded in the shape-changing body.

Detailed description

covering devices for covering and / or To fill of joints between vehicle surfaces and methods for their use are described herein. Further use the joint capping devices disclosed herein advantageously the use of active materials. The joint cover devices include one or more active materials allowing / allowing that the cover devices in response to a change in a Property of the active materials after receiving an activation signal reversibly change a shape and / or rigidity within a joint between vehicle surfaces. Of the Term "areas" as used herein refers generally to all surfaces of a vehicle (inside or outside), which meet to form a fugue (that is, a gap, an opening, a gap and the like), to cover the desirable is. For example, without being limited to where a door panel, a trunk lid, a hood, a window or a tailgate meets the vehicle body. In another example, where a sunroof, a sunroof or the like on the vehicle roof meets. In yet another example, where a glove box and a dashboard or other adjacent surfaces in the passenger compartment, the joints form, such. B. a center console, a storage compartment like z. For example a cupholder, card holder or media storage and the same meeting. The term "active material" as used herein refers generally to a material that after applying a Activation signal a reversible change of at least one property such as B. a dimension, a shape, a phase, an orientation, a stiffness and the like shows. Suitable active materials include without limitation Shape memory polymers (SMPs), shape memory alloys (SMAs), ferromagnetic shape memory alloys (MSMAs), electroactive polymers (EAPs), magnetorheological (MR) Elastomers and the like. Dependent Of the specific active material, the activation signal without restriction the form of an electric current, an electric field (voltage), a temperature change, a magnetic field, a mechanical load or stress and the like.

As As used herein, the terms "first," "second," and the like also no order or importance, but rather serve to distinguish one element from another, and the terms "the", "an" do not designate Limitation of a quantity, but rather designate the presence at least one of the elements referred to. The Indication "about", in connection used with a size is understood, including the specified value and has the meaning determined by the context (includes, for example, the degree of error associated with the measurement of the particular size). Furthermore shut down all of the areas disclosed herein include and are the endpoints individually combinable.

The change the "form" as used herein generally refers to either deformation, such as bending or a change the dimensions of the Fugenabdeckvorrichtung. The change of "stiffness" as used herein generally applies without restriction a change the flexibility, stiffness, compactness, elasticity, strength, the hardness, the density, the speed, the stretching force, the extensibility etc. the joint cover device. The terms "movement", "tried Motion "or" Transformation / Change / Transition "include, without limitation, one Reference to a displacement or deformation resulting from a Force results that exercised will if an area pressed pulled, compressed, twisted or the like.

In an embodiment is a joint-covering body inside or above a joint lying between a first surface and a second surface arranged. The body can be stuck to the first surface or the second surface to be appropriate. In an alternative embodiment, the Fugenabdeckkörper both be mounted on a first and on a second surface. The joint-covering body is designed to be between a first shape and a second one Change shape so that the joint body deforms and its coverage / cover keeps the joint / gap between the two surfaces upright. The Deformation of the joint-covering body leaves a movement of a selected one of surfaces or from both.

In an exemplary variant of this embodiment, an active material is in functional The invention relates to a joint with the joint body, wherein the active material is designed to undergo a change of at least one property upon receipt of an activation signal, wherein the change of the at least one property is effective to transfer the joint body from the first mold to the second mold. In one embodiment, the joint-covering body comprises an active material. In another exemplary embodiment, the active material is a shape memory alloy (SMA) wire. When one or both surfaces are rotated or removed from their original position, the joint cover body is deformed and stretches the SMA wire while in a low modulus condition at room temperature. The wires are heated after returning one or both surfaces to their original position. The SMA wire is thereby straightened to its original first, shorter length and the joint-covering body is returned to the position in which it covers the joint. In another exemplary embodiment, the joint-covering body comprises strips of active materials embedded in the joint-covering body. The embedded active material may be any material that is capable of changing the shape from a first shape to a second shape, and that is suitable for any deformation of the joint covering device to permit easy movement of one or both surfaces after application of the joint corresponding outer field (normal state field off) or returning the joint cover device to its original shape upon return of the surfaces to their original position (normal state field on). Exemplary materials include, but are not limited to, piezopolymers, electroactive polymers (EAPs), and magnetorheological elastomers.

In a further embodiment is a joint-covering body arranged within a joint between a first surface and a second surface. The body can be stuck to the first surface or the second surface to be appropriate. In an alternative embodiment, the Fugenabdeckkörper on both of a first and a second surface be attached. The joint-covering body is designed to be between a first stiffness and a change second stiffness, so that the joint body itself deformed and the overlap / cover maintains the gap / gap between the two surfaces, if one or both surfaces to be moved. The change The stiffness of the joint-covering body allows movement a selected one from one of the surfaces or both.

In an example of this embodiment is the joint cover body even an active material. The body is in the gap between the two surfaces is present, arranged and is firmly attached to one or both surfaces appropriate. In an exemplary embodiment, the active material is a Shape memory polymer. The hinge-like memory polymer is heated, to soften, with one movement (eg a rotation) one the or both surfaces the joint is allowed. If one or both surfaces in their original position brought back can, the Fugenabdeckkörper cooling down and its original Stiffness is restored. In an exemplary application this embodiment is the joint cover body in a joint between two door panels a vehicle positioned. After heating, the Fugenabdeckkörper is made a shape memory polymer soft and leaves a movement of one or both of the door panels to where the Fugenabdeckvorrichtung with the movement of the sheets in the state with reduced Stiffness can bend or sag. After the sheet (s) in his / her original one Position returned is / are, d. H. after closing a door, that cools Fugenabdeckkörper off and will be in its original Stiffness returned. That for the joint cover body used active material may be any material whose Stiffness after heating and cooling would change. In an exemplary embodiment For example, the active material is a shape memory polymer. In a second exemplary embodiment is the active material in which the stiffness in response on a heating / cooling changes, one Shape memory alloy. As long as the stretch of the SMA is small, it elasticizes deformed, a change occurs Stiffness only on when over / under their transition temperature heated / cooled. In yet another possible embodiment For example, an MR elastomer may change in response to a magnetic field experienced rigidity and therefore explained similar to the others embodiments to exert an effect on the Fugenabdeckvorrichtung.

In a further variant of this embodiment, the joint cover body is disposed within the joint and fixedly attached to one or both of the surfaces and includes a shape memory alloy having a low transition temperature. This embodiment can therefore utilize the superelastic property of the SMA. When the SMA is in its austenitic form at normal operating temperature, stress in the SMA due to the attempted movement of either or both of the surfaces will cause the SMA to change to its lower modulus martensitic shape, thereby causing relative movement of the SMA Areas allows. Removing the tension inducing force from the surface, either by returning the surfaces to their original position or by simply pulling the back Holding force that holds the surfaces in their new relative positions, will cause the SMA to simultaneously return to the austenitic form with its higher stiffness, thereby returning to its original geometry. This embodiment uses the superelastic effect of SMA.

In a still further exemplary variant of this embodiment can the joint cover body, which is placed inside the joint and fixed to one or both from the surfaces The joint is made of a magnetorheological elastomer be formed. In one example, the activation signal, in In this case, a magnetic field on which MR elastomer can be present and cause that the material is a higher Having stiffness. When the movement of one surface in relation to the other he wishes is, the magnetic field can be removed, reducing the stiffness reduces the MR elastomer and is allowed by the surface movement is deformed. If the area (s) in the original one Home position returns, The magnetic field can be reapplied to the MR elastomer to his original higher To return stiffness. In an alternative second example, the magnetic field be removed under normal conditions. When the field is activated the MR elastomer can bend or otherwise deform, that it allows a relative movement of the one or both surfaces, the define the boundaries of the joint. Removing the magnetic Feldes causes the MR elastomer the joint cover body in its joint-covering initial shape, whereby the elastic Nature of the material is used.

In a preferred embodiment the change takes place from a first stiffness to a second stiffness of the joint covering device, without that the joint is exposed, thereby allowing the Fugenabdeckvorrichtung acts as an invisible hinge. In another preferred embodiment, the joint covering spans Device the joint, d. h., produces a continuous area without a visible joint, which also makes it an invisible hinge acts.

In a third embodiment The present disclosure comprises a joint cover body which arranged inside the joint and fixed to one or both of the surfaces is attached, an active material attached to the outside of the Fugenabdeckkörper is. The joint cover body can after a movement of one or both of the surfaces a change (i.e., a deformation) learn the form. Upon receipt of an activation signal, the Outside attached active material the joint cover body in its original Return shape (i.e., initial geometry). The outside attached active material may, for. As an SMA wire, the solid area independently from the joints producing surfaces is anchored. After receiving an electrical signal may turn the SMA wire in one length dimension contract and thereby the Fugenabdeckkörper in its original joint-covering Pull the form.

The active material of the joint covering device can be more functional Remote connection with the device stand, or the active material can be integrated into the device. For example, the active Material on a surface of changeable form body, embedded within the area of changeable form body, embedded within the deformable body itself, or outside with the area be arranged connected to the Fugenabdeckvorrichtung. Furthermore the covering device may comprise one or more active materials, the as a coating, a layer, sections such. B. Strips of an active material, on at least one surface of the material variable in shape body is / are. Alternatively, the shape changeable body the Fugenabdeckvorrichtung completely made of the active material. Furthermore you can various active materials applied to the surface of the deformable body with the various active materials adjacent to one another are applied. In a further embodiment, the active Material comprise a composite of different shape memory materials. The active material provides the cover device with a formability that can be actively tuned to a particular application, as below standing in greater detail is described. The described active materials can be a essentially straight shape at room temperature and a curved shape (i.e., curved shape) when over a range of temperatures to be heated generally during a vehicle operation or the use of a device / application can be present (in this way, the actively controlled activation locked out).

The Fugenabdeckvorrichtung based on an active material can any of a variety of configurations including, but not limited on a flexible flap, a rigid plate, a shape changeable Pipe, a shaped hollow cross section and the like, wherein the Design is suitable to joints between two vehicle surfaces outside or inside the vehicle.

The active material may have at least one property in response to an activation signal and, upon discontinuing the activation signal, return to the initial state of the at least one property, or, for the classes of active materials that do not automatically return after interrupting the activation signal, an alternative means may be used to return the active materials to their original state return. For embodiments in which the active material is activated by an attempted movement of one of the surfaces, the active material may return to the original state of at least one property after the surface has returned to its original physical position, ie activation of the active material Opening the door and deactivating when closing the door. The above-mentioned suitable active materials for use in the capping devices will be explained in more detail below.

With the cover device coupled based on an active material and in functional connection with this is an activating device, which may be connected to a control system. The activation device serves to selectively apply an activation signal to the capping device to provide the basis of an active material and a feature the cover device based on an active material by changing at least one Property of the active material to change. For example, that can active material, depending of whether a button to open the vehicle hood pressed will, become more or less rigid. The activation device if necessary, turns on the activation signal or a stimulus the active material of the covering device based on an active Materials ready to make the change one or more features of at least a portion of the device to effect. In one embodiment remains the change a feature in general for the duration of the applied activation signal exist. After interruption of the activation signal generally reverses the active material disabled form back and essentially returns to the at least one original one Property back and thus brings the cover on the basis of an active material to the original feature and / or features back. If, however, the external force and / or stress applied at the time of deactivation will be, for certain Materials such. For example, an SMP will be the property after deactivation in the new desired Form locked. In this way can advantageously reversible and several provisions the covering arrangements are based on an active material.

The activation signal provided by the activation device can be a heat signal, a magnetic signal, an electrical signal, a pneumatic Signal, a mechanical signal, a chemical signal and the like and combinations with at least one of the preceding signals comprising the special activation signal from the materials and / or the design of the active material is dependent. For example, a heat signal be created to the property of an SMA and / or a To change SMP produced active material. An electrical signal (Voltage) can be applied to the property of the active To change materials made from EAPs and a piezoceramic and piezopolymers is. A magnetic field can be applied (removed or changed), to the property of magnetostrictive materials such. B. MSMA and MR elastomers produced active material or using a different tax system.

The Activation device can be operated in many ways. For example, in an embodiment the use of the remote keyfob for locking / unlocking a vehicle door also be designed to trigger the activation signal and the reduction / increase the size and / or To effect rigidity of Fugenabdeckvorrichtung. Likewise, a wireless could Signal transmitter in the key fob in Combination with an activation device sensor can be used to automatically activate the active material when the key fob is in physical proximity brought to the covering device based on an active material which eliminates the need to press key chain buttons. In a further embodiment could the activation signal is activated manually. For example, that could Inserting the vehicle key in the door lock or the use of an inner door handle the activation signal activate. In similar Way could a push button or the like arranged adjacent to the joint being a depression the push button activates the activation signal to the size and / or To change the rigidity of the joint material. In each of the above Method for activating the active material may be the activation signal by an interruption of a timer in conjunction with the Covering device based on an active material or by a sensor in functional communication with the device or by the occurrence of a particular event, e.g. B. an opening and Shut down the vehicle door, be turned off to disable the activation signal and reset the device to its original state.

In the embodiments where attempted movement of one of the surfaces results in a change in rigidity of the joint-covering device, the change in rigidity may Result of the superelastic property of the SMA. Starting with an SMA in its austenitic form at room temperature, the application of force to a first surface or surface connected to the SMA material joint-covering device will cause stress-induced switching of the SMA into its lower modulus martensitic form and then allow relative movement of the adjacent sheet metal parts by superplastic deformation of the SMA. Removal of the applied force would return the SMA material to its original state, both in terms of geometry and rigidity.

Independent of the activation mode, it is advantageous that the Fugenabdeckvorrichtung based on active material in passive mode, i. H. if no power or activation signal is present on the device is, in her original one Condition remains. If no movement is adjacent to one or both surfaces desired to the joint and no activation signal is applied to the active material is no performance for the permanent cover of the joint necessary. In other words, the only performance that the cover device based on a active material needed is for the short duration in which the device must change the property which allows a movement at the joint, like. z. B. reducing the stiffness at the joint to open a door in the case of a door panel.

In a further embodiment includes the covering device based on an active material at least one sensor in functional communication with the device and / or the active material, wherein the sensor is formed, to transmit signals indicate the at least one vehicle condition. A vehicle condition may mean when the vehicle is parked or moving, or if a part or an accessory of the vehicle between states changes, z. B. if a door open or closed. This embodiment may further include a Include controllers that are functional with the sensor and the activation device The controller is programmed and configured is to cause the activation device to be an activation signal to the active material when the sensor signals a predetermined vehicle condition or a necessary configuration show the two areas. The size of the changed Property as well as the rate of change (or profile) can through the control system will be determined.

The Active material can be any of a variety of active materials include, including but not limited on shape memory materials, z. B. shape memory alloys, Shape memory polymers and electroactive polymers, polymer-metal composites, conductive polymers, Magnetorheological (MR) compositions such. B. MR elastomers, Piezoceramics, piezopolymers and other similar materials after receiving an activation signal, a change at least show a property. The present disclosure is not intended to be limited to any particular active material and / or combinations of active materials limited be. Equally intended the present disclosure is not limited to any particular activation signal limited be. The special activation signal or the combinations thereof is / are from the sensitivity of the active material and / or the preferred method and / or the rate or degree of change (or the profile) of the necessary feature. For example, can a SMA thermally by means of an ohmic (electrical resistance) heating and / or convective use of fluid heating are thermally activated.

Around To better understand the different types in which a Fugenabdeckvorrichtung Active materials can use to make a joint between two surfaces reversible It is necessary to cover the essence and mechanics of the desirable to understand active materials. As mentioned above, suitable active ones include Materials for the covering devices based on an active material without Limitation shape memory alloys ("SMAs", eg thermal and stress-activated shape memory alloys and magnetic shape memory alloys (MSMA)), electroactive polymers (EAPs) such. B. dielectric elastomers, ionic polymer metal composites (IPMC) and shape memory polymers (SMPs), shape memory ceramics (SMCs), baroplastics, magnetorheological (MR) materials (e.g. Fluids and elastomers), piezoceramics, piezopolymers, compositions the previous active materials with non-active materials, Systems containing at least one of the previous active materials include, and combinations that are at least one of the previous ones active materials. For the sake of simplicity and example herein is based on shape memory alloys and shape memory polymers Referenced. The shape memory ceramic, Baroplasts and the like can on a similar one Be used way. For example, in case of baroplasty Materials a pressure-induced mixing of nanophase domains of High and low glass transition temperature (Tg) components Strain. Baroplasts can at relatively low temperatures repeated without deterioration are processed.

The ability of shape memory materials to return to their original shape after the application or removal of external stimuli has become ih Used in actuators to apply force that leads to a desired movement. Active material actuators offer the potential of reducing size, weight, volume, cost, noise, and increasing the robustness of the actuator as compared to traditional electromechanical and hydraulic actuators. Ferromagnetic SMAs, for example, show rapid dimensional changes of up to several percent in response to an applied magnetic field (and proportional to its magnitude). However, these changes are unidirectional and utilize the application of either biasing force or field reversal to return the ferromagnetic SMA to its initial configuration.

Shape Memory Alloys are alloy compositions with at least two different ones temperature-dependent Phases or polarity. The most common used of these phases are the so-called martensite and the Austenite phase. In the following explanation, the martensite phase refers generally to the stronger deformable phase of lower temperature, whereas the austenite phase generally refers to the more rigid phase of higher temperature. If yourself the shape memory alloy is located in the martensite phase and is heated, it begins to to change to the austenite phase. The temperature at which this phenomenon starts is often called Austenite start temperature (As). The temperature, at the this phenomenon is often referred to as austenite finish temperature (Af). If yourself the shape memory alloy When it is in the austenite phase and is cooled down, it begins to to change into the martensite phase, and the temperature at which this phenomenon begins is often called Martensite start temperature (Ms). The temperature, at that the austenite stops, to pass into martensite will often referred to as martensite final temperature (Mf). The area between As and Af is often referred to as the martensite-to-austenite transition temperature range designated while which is often referred to as the austenite-to-martensite transition temperature range between Ms and Mf becomes. It should be noted that the transition temperatures mentioned above Functions of the voltage are the SMA sample experiences. Generally these temperatures increase with increasing voltage. In terms of on the preceding properties is a deformation of the Shape memory alloy preferably at or below the austenite start temperature (at or below As). A subsequent one He warms over the Austenite start temperature causes the deformed shape memory material sample begins to finish at the final austenite temperature in their original one to return (unstressed) permanent shape. Thus, a suitable s Activation input or signal for use with shape memory alloys a thermal activation signal of a magnitude sufficient to temperature-dependent transitions between the martensite and austenite phases.

The Temperature at which the shape memory alloy adapts to its high temperature shape recalls (that is, its original, not strained shape), when heated, may be subject to minor changes in the composition of the alloy and by thermomechanical Processing to be adjusted. In nickel-titanium shape memory alloys can she z. B. from about about 100 ° C be changed to below about -100 ° C. The shape recovery process can span a range of only a few Gradual or more gradual recovery over one larger temperature range demonstrate. The beginning or the end of the transformation can be within several Grade, depending on the desired Application and alloy composition, controlled. The mechanical Shape memory alloy properties vary strong over the temperature range that spans their conversion, and typically provide one Shape memory effect and a super-elastic effects ready. For example, in the Martensite phase has a lower elastic modulus than in the austenite phase observed. Shape Memory Alloys in the martensite phase by realigning the crystal structure assembly with the deposited one Tension big Undergoing deformations. The material retains this shape after the tension was removed. In other words, through Voltage induced phase changes in the SMA, they are two-way in nature; the application of sufficient tension when an SMA is in its austenite phase is a change into their lower modulus martensite phase. The removal The applied voltage will cause the SMA to enter its austenite phase switches back and thus regain their initial form and the higher module.

Exemplary shape memory alloy materials include nickel titanium based alloys, indium titanium based alloys, nickel aluminum based alloys, nickel gallium based alloys, copper based alloys (e.g., copper-zinc alloys, copper-aluminum alloys , Copper-gold and copper-tin alloys), gold-cadmium-based alloys, silver-cadmium-based alloys, indium-cadmium-based alloys, manganese-copper-based alloys, iron-platinum-based alloys , Iron-palladium-based alloys and the like. The alloys may be binary, ternary, or of any higher order provided that the alloy composition has a shape memory effect, such as a shape memory effect. B. a change in the shape, the orientation, the yield stress, the bending modulus, damping capacity, superelasticity and / or similar properties. The choice of a suitable shape memory alloy composition will depend in part on the temperature range of the intended application.

The recovery in the austenite phase at a higher Temperature is accompanied by very high voltages (in comparison with those needed to deform the material), that can be so high like the natural one yield of austenite material, sometimes up to triple or more the deformed martensite phase. For Applications that are a big one Number of operating cycles may require an elongation of less than or equal to 10% or so of the deformed length of the used wire are obtained. MSMAs are alloys that often consist of Ni-Mn-Ga and the shape as a result of a magnetic Change field induced strain. MSMAs have internal variants with different magnetic and crystallographic orientations. In a magnetic field change the proportions of these variants, resulting in a change in the overall shape of the Materials leads. An MSMA actuator generally requires that the MSMA material be between the coils of an electromagnet is arranged. The electric Electricity flowing through the coil induces a magnetic field through the MSMA material that causes a change the shape causes. An exemplary MSMA may be a Ni-Mn-Ga foam be. The MSMA foam may have a bamboo-like texture that extends up to extend to 10% (i.e., stretch) when a magnetic field is applied. The Foam material reserves its new stretched shape when the field is removed, the magnetic However, delicate atomic structure may be in their original Form return, though the field is rotated 90 degrees. The porous nature of the foam reinforces the Deformation effect. The Ni-Mn-Ga-MSMA foam can be produced by the molten Alloy is poured into a part of a sodium aluminate salt. If the material cooled is an acid can be used to wash out the salt, leaving behind large voids and thus the foam-like Structure is formed.

As previously mentioned, For example, other exemplary shape memory materials are shape memory polymers (SMPs). "Shape memory polymer" refers generally on a polymer material, which upon application of an activation signal a change a property such as B. a module, a dimension, a coefficient of thermal expansion, moisture permeability, an optical property (eg translucence), or a combination, the at least one of the preceding properties in combination with a change in its microstructure and / or morphology, shows. Shape memory polymers can heat sensitive (ie, the change the property is caused by a thermal activation signal that either directly over a heat supply or -abfuhr or indirectly via a vibration with a frequency that is suitable for high vibration amplitudes to stimulate at the molecular level, which leads to an internal heat generation to lead, supplied), photosensitive (i.e., the change of the property becomes caused by an electromagnetic radiation activation signal), sensitive to moisture (that is, the change of property is due to a liquid activation signal such as As moisture, water vapor or water causes), chemically sensitive (i.e., sensitive to change) the concentration of one or more chemical species in it Environment, z. B. the concentration of H + ions, ie the pH of the environment) or a combination that is at least one of the preceding ones includes.

in the Generally, SMPs are phase separated copolymers that are at least comprise two different units which can be described as they define different segments within the SMP, each one Different from the overall properties of the SMP. As As used herein, the term "segment" refers to a block, a peg or a peg Sequence of the same or similar Monomer or oligomer units copolymerized to form the To form SMP. Each segment can be (semi-) crystalline or amorphous and becomes a corresponding melting point or a glass transition temperature (Tg). The term "heat transfer temperature" will be used herein simply generally used to either a Tg or a melting point Depending on whether the segment is an amorphous segment or a crystalline segment. For SMPs that include (n) segments, can be said that the SMP is a hard segment and (n - 1) soft Segments, wherein the hard segment has a higher heat transfer temperature has as each soft segment. Thus, the SMP (n) has heat transfer temperatures on. The heat transfer temperature of the hard segment is referred to as the "last transition temperature" and the lowest heat transfer temperature of the so-called "softest" segment is called It is called the "first transition temperature." It is important to point out that if the SMP has multiple segments characterized by the same heat transfer temperature, which is also the last transition temperature is, it can be said that the SMP several has hard segments.

If the SMP is heated above the last transition temperature, the SMP material can be given a permanent shape. A per The SMP's inherent shape can be fixed or memorized by subsequently cooling the SMP below this temperature. As used herein, the terms "original shape", "predefined shape", "predetermined shape" and "permanent shape" are synonymous and intended to be used interchangeably. A temporary shape may be determined by heating the material to a temperature higher than a heat transfer temperature of any soft segment but below the last transition temperature, applying an external stress or strain to deform the SMP, and is then cooled below the certain heat transfer temperature of the soft segment while maintaining the deforming external stress or load.

The permanent shape can be regained by the material while the Voltage or load is removed beyond the specific heat transfer temperature of the soft segment, but is heated below the last transition temperature. It should therefore be appreciated that it can be done by combining several soft segments is possible, several temporary ones Showing shapes, and with multiple hard segments, it may be possible to have several to show permanent forms. In a similar way is when using a batch with a layer or a Combining a combination of multiple SMPs transitions between multiple temporary and show permanent forms.

MR fluids are a class of intelligent materials whose theological Properties can change quickly when creating a magnetic field (z. B. can property changes hundreds of percent within a few milliseconds), what they are very suitable for confining (restricting) or allowing relaxation molds / deformations by a significant change in their shear strength makes, with such changes useful for grasping and releasing objects in Embodiments described herein are. Exemplary shape memory materials also include magnetorheological (MR) and ER polymers. MR polymers are suspensions of magnetically polarizable micron sized particles (e.g. ferromagnetic or paramagnetic particles as described below) in a polymer (eg a thermoset elastic polymer or rubber). Exemplary polymer matrices include polyalphaolefins, Natural rubber, silicone, polybutadiene, polyethylene, polyisoprene and combinations with at least one of the foregoing.

The Stiffness and under certain circumstances the shape of the polymer structure are achieved by the shear and Compression / tensile moduli are changed by the strength of the applied magnetic field is varied. Develop the MR polymers their stiffness typically when they are a magnetic field as short as a few milliseconds are exposed, where the stiffness and shape changes to the strength proportional to the applied field. Are the MR polymers no longer the exposed to magnetic field, the process reverses and that Elastomer returns to its lower modulus state.

MR fluids show a shear strength that is proportional to the size of a applied magnetic field, wherein the property changes of several hundred percent within a few milliseconds can be. Although with these materials the problems with the compact Accommodating the required to generate the applied field Coils can exist they as blocking or release mechanism for z. B. a spring-based Grabbing / releasing are used.

Suitable MR fluid materials include ferromagnetic or paramagnetic particles suspended in a support, e.g. In an amount of about 5.0% by volume (vol%) to about 50% by volume based on the total volume of the MR composition. Suitable particles include iron; Iron oxides (including Fe ₂ O ₃ and Fe ₃ O ₄ ); Iron nitride, iron carbide, carbonyl iron; Nickel; cobalt; chromium dioxide; and combinations comprising at least one of the foregoing; z. B. nickel alloys; Cobalt alloys; Iron alloys such. As stainless steel, silicon steel, as well as others, including aluminum, silicon, cobalt, nickel, vanadium, molybdenum, chromium, tungsten, manganese and / or copper.

The Particle size should be so chosen be that the particles show properties of multiple magnetic domains, when exposed to a magnetic field. The particle diameter (z. As measured along a major axis of the particle) may be smaller or equal to about 1000 microns (microns) (e.g., about 0.1 microns to about 1000 microns), or more preferably about 0.5 to about 500 microns, and more particularly about 1 to about 100 microns.

The viscosity of the carrier may be less than or equal to about 100,000 centipoise (cps) (eg, about 1 cps to about 100,000 cps) or, more specifically, about 250 cps to about 10,000 cps, or more specifically, about 500 cps to about 1,000 centipoise. Possible carriers (eg carrier fluids) include organic liquids, in particular non-polar organic liquids. Examples include oils (e.g., silicone oils, mineral oils, paraffin oils, white oils, Hy draulic oils, transformer oils and synthetic hydrocarbon oils (eg unsaturated and / or saturated)); halogenated organic liquids (such as chlorinated hydrocarbons, halogenated paraffins, perfluorinated polyethers and fluorinated hydrocarbons); diester; polyoxyalkylenes; Silicones (eg fluorinated silicones); cyanoalkyl siloxanes; glycols; and combinations comprising at least one of the listed carriers.

It can also watery carrier be used, especially those containing hydrophilic mineral Clays such as B. bentonite or hectorite. The aqueous carrier can Water or water that is a polar, water-miscible organic solvent (eg, methanol, ethanol, propanol, dimethylsulfoxide, dimethylformamide, Ethylene carbonate, propylene carbonate, acetone, tetrahydrofuran, diethyl ether, Ethylene glycol, propylene glycol and the like) as well Combinations comprising at least one of the mentioned carriers. The amount of organic solvent in the carrier can be less than or equal to about 5.0 vol.% (eg, about 0.1 vol about 5.0% by volume) based on the total volume of the MR fluid or more preferably about 1.0% to about 3.0%. Of the pH of the aqueous carrier can be less than or equal to about 13 (eg, about 5.0 to about 13) or more particularly about 8.0 to about 9.0.

If the watery carrier natural and / or Synthetic bentonite and / or hectorite may include the amount to clay (bentonite and / or hectorite) in the MR fluid less than or equal to about 10 weight percent (wt.%) based on a Total weight of the MR fluid or, more specifically, about 0.1% by weight to about 8.0 wt%, or more preferably about 1.0 wt% to about 6.0 wt%, or more preferably about 2.0 wt% to about 6.0 wt%.

optional Components in the MR fluid include clays (eg, organophilic clays), Carboxylate soaps, dispersants, corrosion inhibitors, lubricants, Anti-wear additives, Antioxidants, thixotropic agents and / or anti-settling agents. carboxylate include iron oleate, iron naphthenate, iron stearate, aliuminium di and tristearate, lithium stearate, calcium stearate, zinc stearate and / or sodium; surfactants Substances (eg sulfonates, phosphate esters, stearic acid, glycerol monooleate, Sorbitan sesquioleate, laurates, fatty acids, fatty alcohols, fluoroaliphatic Polymerester); and adhesion promoters (eg, titanate, aluminate, and zirconate); as well as combinations comprising at least one of the foregoing. Also polyalkylene diols such. As polyethylene glycol and partially esterified polyols can to be included.

electronic Electroactive polymers (EAPs) are a laminate of a pair of electrodes with an intermediate layer of a dielectric Ma material with a low modulus of elasticity. Application of a potential between the electrodes presses the intermediate layer together and causes it to expand in the plane. they show a response that is proportional to the applied field, and can operated with high frequencies become. shape-Changing EAP laminate films were demonstrated. Your main disadvantage exists in that they require applied voltages that are around three orders of magnitude are bigger as those needed by a piezoelectric. Electroactive polymers include those polymeric materials that respond in electrical or mechanical fields piezoelectric, pyroelectric or electrostrictive Have properties.

Materials, which are suitable for use as an electroactive polymer, can comprise any substantially insulating polymer and / or rubber, that deforms in response to an electrostatic force or its deformation to a change an electric field leads. Exemplary materials for use as a pre-stretched Include silicone elastomers, acrylic elastomers, Polyurethanes, thermoplastic elastomers, copolymers with PVDF, pressure-sensitive adhesives, fluoroelastomers, and polymers Silicone and acrylic components include (e.g., copolymers with silicone and acrylic components, Polymer blends with a silicone elastomer and an acrylic elastomer and the same).

Materials that are used as an electroactive polymer may be based on one or more material properties, such as, for example, A high electric breakdown field strength, a low elastic modulus (eg, for large or small deformations), a high dielectric constant, and the like. In an embodiment, the polymer may be selected such that it has a modulus of elasticity of at most about 100 MPa. In another embodiment, the polymer may be selected to have a maximum actuation pressure of between about 0.05 megapascals (MPa) and about 10 MPa, or more specifically between about 0.3 MPa and about 3 MPa. In a further embodiment, the polymer may be selected to have a dielectric constant between about 2 and about 20, and more particularly between about 2.5 and about 12. The present disclosure is not intended to be limited to these areas. Ideally, materials with a higher dielectric constant than the ranges indicated above would be desirable if the materials had both a high dielectric constant and a high dielectric strength. In many cases you can electroactive polymers be prepared and implemented as thin films, the z. B. have a thickness of less than or equal to about 50 microns.

There electroactive polymers should be able to flex at high strains electrodes attached to the polymers also bend, without affecting the mechanical or electrical performance. In general, you can suitable electrodes for use and have any shape Any material, provided they are capable of a suitable Supplying voltage to or from an electroactive polymer to receive an appropriate voltage. The tension can either be constant or change with time. In one embodiment the electrodes stick to a surface of the polymer. Electrodes that can stick to the polymer docile be and be changing Adjust the shape of the polymer. The electrodes can only be on one section be applied to an electroactive polymer and an active surface according to their Define geometry. Various types of electrodes include structured electrodes with metal traces and charge distribution layers, textured electrodes, conductive Pastes (eg, coal pastes or silver pastes), colloidal suspensions, conductive High aspect ratio materials (e.g., carbon nanotubes and Mixtures of internal conductive Materials), as well as combinations that are at least one of the preceding include.

exemplary Electrode materials can be graphite, Soot, colloidal Suspensions, metals (including silver and gold), filled gels and polymers (e.g., silver filled and carbon filled Gels and polymers) and ionically or electronically conductive polymers as well as combinations with at least one of the preceding ones. It can be seen that certain electrode materials with certain Polymers can work well and can not work so well with others. For example, work Carbon filaments go well with acrylic elastomer polymers and not so good with silicone polymers.

Magnetostrictives are solids, which develop a strong mechanical deformation when subjected to an external magnetic Be subjected to field. This phenomenon of magnetostriction is attributed to the rotations of small magnetic domains in the materials the random ones are oriented when the material is not exposed to a magnetic field is. The shape change is greatest at ferromagnetic or ferromagnetic solids. Own these materials a very fast response, wherein the strain is proportional to the magnitude of the applied magnetic Field is, and they return to their fields after removing the field Initial dimension back. However, these materials have maximum strains of about 0.1 to about 0.2 percent.

Referring now to 1 For example, an exemplary embodiment of an active material based capping device is shown and generally designated by the reference numeral 12 designated. In this embodiment, the device comprises the joint covering body 12 , which directly with the adjacent surfaces such. B. the first surface 4 and / or the second surface 8th connected and the fugue 6 partially filled. In another example, the Fugenabdeckkörper 12 instead of the fugue 6 partially or completely fill, cover the joint by covering the edges of the first and second surfaces, which the joint 6 form. The device 12 can still work in the same way; the only difference is the arrangement of the cover body. The joint cover body 12 includes an active material. The active material, completely the body 12 may include or only broken stripes or the like within the body 12 is adapted to undergo a change of at least one property upon receipt of an activation signal, wherein the change of a property is effective to the joint covering body 12 to transfer between a first mold (a) and a second mold (b). A movement of the plane 8th (as in 1 (b) shown) will deform the joint cover body from the first mold into the second mold. Activation of the active material within the body 12 may be effective to bring the body from the second shape back to the first shape. In a variant of this embodiment, the active material may be a shape memory alloy. The Fugenabdeckkörper this embodiment is advantageous to cover joints where the surface aesthetics may be important, such. B. between the outer body panels of a vehicle. The joint cover body 12 may be painted and / or shaped to resemble the surrounding first and second surfaces. The change in the shape of the joint covering body may be a reduction or expansion of the size, the volume, the length or another physical dimension, so that a free movement of the disclosed surfaces would be permitted and / or a movement of adjacent surfaces is reversibly restricted.

An activation device 11 can be used to send the activation signal to the active material 2 to deliver. Likewise, a controller 13 and a sensor 14 in functional communication with the activation device 11 be used so that all the components together and with the Fugenabdeckkörper 12 work on the basis of an active material to initiate changes in at least one property of the active material.

With reference to 2 Another exemplary embodiment of a joint cover body is illustrated and generally indicated by the reference numeral 22 designated. In this embodiment, the Fugenabdeckkörper sits 22 within the fugue 16 and is directly with one of the adjacent surfaces such. B. the area 15 connected. The joint cover body 22 includes an active material 24 , The active material, completely the body 22 may include or only broken stripes or the like within the body 22 is adapted to undergo a change of at least one property upon receipt of an activation signal, wherein the change of a property is effective to the Fugenabdeckkörper 22 between a first stiffness (a) and a second stiffness (b) the one movement of the surface 18 allows to transfer.

In a variant of this embodiment, the Fugenabdeckkörper a second body 20 include, which may be formed of an active material or not. The joint cover body 22 may be the connecting material, in which case it is with the second body 20 connected, so the second body 20 the visible material is the fugue 16 covers. The second body 20 is advantageous to cover joints, where the surface aesthetics may be important, such. B. between the outer body panels of a vehicle. In this case, the second body 20 may be formed of a material that is easier to paint and / or shape than the active material used to resemble the surrounding first and second surfaces.

In an example of the above embodiment, the joint cover body 22 include an SMP. The SMP can be softened to a second stiffness by applying a heat signal to a movement of the surface 18 permit. After the area 18 has returned to its original position, with the warm signal still applied, the body becomes 22 return to its original shape, and then the heat signal can be removed from the SMP, thus causing the SMP to return to the first stiffness. In a further embodiment, the joint cover body 22 an MR elastomer and / or an MR fluid. The MR elastomer / fluid can be softened to a second stiffness by removing a magnetic field that reduces the stiffness and / or shear strength of the joint cover body, thereby allowing relative movement of the adjacent surfaces. Application of the magnetic field may return the MR elastomer / fluid to its original stiffness covering the joint after one or more of the surfaces have been returned to their original positions.

In an alternative embodiment, the in 3 As shown, an active material-based capping device is generally indicated by the reference numeral 60 designated. In this embodiment, the Fugenabdeckkörper sits 62 within a fugue 64 and is directly with both adjacent surfaces 66 and 67 connected. An active material 68 is outside with the Fugenabdeckkörper 62 connected. In an embodiment, the active material comprises 68 an SMA wire that is stuck between the body 62 and a solid surface 70 is appropriate. As used herein, the term "wire" is intended to mean, in general, any geometric shape that is suitable between the body 62 and the area 70 to be attached. The examples include, without limitation, cables, strips, springs, and other similar geometric shapes. The SMA wire 68 is configured to undergo a change in a length dimension upon receipt of an activation signal. Moving one or both of the surface 66 and 67 becomes the body 62 deformed from a first shape to a second shape, while the SMA wire 68 to stretch or otherwise deform. An activation of the SMA wire 68 can the joint cover body 62 after receiving an activation signal return to its original shape (ie the initial geometry). The SMA wire attached to the solid surface 70 is anchored, can contract after receiving an electrical signal in a length dimension and thereby pull the Fugenabdeckkörper back to its original, covering the joint shape.

For those in the 1 . 2 and 3 In embodiments shown, the joint cover body may be configured to respond to an attempted movement of one or both of the surfaces, being allowed to deform during a subsequent further movement of one or both of the surfaces.

In yet another embodiment, the change of at least one property of the body of active material may be reversed so that heating is required to allow movement of one or both surfaces at the joint, and reversing to a low temperature will cause immobility at the fugue Effecting a joint. In either case, the change in the at least one property of the active material body may persist after interruption of the activation signal. Furthermore, the covering device can be restored from an active material and returned to a desired shape by the body 102 is heated from an active material to the appropriate temperature. In this way, a covering device based on an active material, which is deformed unintentionally, such as. B. during an impact event, restored and in a desired Form are returned by the appropriate temperature range is applied. The selection of the material comprising the body of active material will be determined by the desired application and will be known to one skilled in the art.

In 4 is an alternative embodiment of a Fugenabdeckkörpers 100 shown, wherein the body comprises strips and / or portions of an active material, which are embedded in a surface. The Stripes 102 of an active material are preferably but not necessarily at regular intervals on the surface of a flexible matrix 104 embedded. In an alternative embodiment, the strips of active material are embedded within the elastic matrix of the joint cover body. The placement of the active material is not limited to any particular configuration or pattern and will be determined by the desired application of the device. In one embodiment, the strips 102 made of an active material strip from an SMA, with the strips 102 of an active material in the austenite phase, a learned curved shape (in the view of 3 not shown). Again, the change in the shape of the active material may be initiated by an activation signal transmitted by an activation device, a controller, a sensor, and / or an attempted movement of at least one adjacent surface.

As a result of the change of phase, the stiffness of the strips 102 of an active SMA material in the austenite phase be greater than the rigidity in the martensite phase. The number and size of embedded stripes 102 of an active material may be chosen such that the embedded active material, when in the austenite phase, causes the majority of the capping device 100 deformed from an active material. If the stripes 102 from an active SMA material but in the martensite phase is the flexible matrix 104 the cover device 100 of an active material is sufficiently rigid to return the device to a straight configuration, with the strips 102 straighten out of the active SMA material. As previously explained, the cover device 100 made of an active material when, due to a force, eg. As an impact or other event that causes plastic deformation, be restored by the strips 102 be heated from an active SMA material to the austenite phase temperature.

The Application and functionality the covering device is based on an active material determine which active material for the particular arrangement at best suited. Factors such as strength, displacement, activation time and the like can used to determine what kind of active material is most suitable. If an application z. B. an activation time may require an SMA or an SMP be suitable. If an application requires shorter activation times, For example, an EAP or an MR elastomer can be used.

As mentioned above, advantageously uses the capping device as disclosed herein advantageously active Materials to size and / or Stiffness of a joint material that is between two adjacent surfaces present, reversibly expose and cover to a relative Movement of surfaces permit. The covering devices based on an active Materials are lightweight, inherently robust, of lesser complexity than existing ones Joint cover devices (the numerous error-prone mechanical and / or have electrical components) and generate little or no noise. The use of active materials to the shape and / or rigidity influencing the devices gives them an increased simplicity, while the Arrangement volume and the energy requirement for activation due to their higher Energy densities are reduced. In addition, those are herein described covering devices based on an active material economical and have a simply adaptive construction, the under minor changes can be integrated into the existing structure.

While the Invention with reference to an exemplary embodiment is described for the skilled person to be aware that various changes can be made and Elements of it by equivalents can be replaced without departing from the scope of the invention. Moreover, numerous modifications be made to a specific situation or material to adapt to the teachings of the invention without departing from the essential scope to deviate from it. The invention is therefore not intended to be specific embodiment limited which is best revealed as the execution of the Invention is conceivable, but the invention includes all embodiments which fall within the scope of the appended claims.

Claims (21)

A device for covering a joint between a first surface and a second surface, the device comprising: a joint covering body fixedly attached to a selected one of the first surface and the second surface, or both, wherein the foot of FIG a masking body comprising an active material, wherein the active material is configured to switch between a first stiffness and a second stiffness upon receipt of an activation signal, the alternation allowing movement of a selected one of the first surface and the second surface or both deforms the Fugenabdeckkörper with the movement of the surface to maintain the cover of the joint. The device of claim 1, wherein the active material changes from the first stiffness to the second stiffness, if it is due to an attempted movement of a selected one of the first surface and the second surface or both is charged. The device of claim 1, wherein the active material a shape memory alloy, a ferromagnetic shape memory alloy, a shape memory polymer, a magnetorheological elastomer, a magnetorheological fluid, an electroactive polymer, a piezoelectric polymer, a piezoelectric ceramic or combinations comprising at least one of the foregoing active materials. Apparatus according to claim 1, wherein the activation signal a thermal activation signal, an electrical activation signal, a magnetic activation signal, a chemical activation signal, a mechanical load or a combination that at least includes one of the preceding activation signals. The device of claim 1, further comprising Activation device, which is designed to activate the activation signal to deliver to the active material. Apparatus according to claim 1, wherein the joint cover body comprises the active material is formed. The device of claim 1, wherein the active material in the joint cover body is embedded. The device of claim 1, wherein the active material Includes sections that are disposed within the Fugenabdeckkörpers are. The device of claim 1, wherein the first surface is a Door panel, a trunk lid, a bonnet, a window, a tailgate, a sunroof, a sunroof, a center console, a storage compartment or a glove compartment. The device of claim 1, wherein the second surface is a Vehicle body panel, a vehicle roof or dashboard includes. Device for covering a joint between a first surface and a second surface, wherein the device comprises: a joint cover body which is formed to switch between a first shape and a second shape, and wherein the change between the first and the second form a Movement of a selected one from the first surface and the second surface or both, so the joint cover body forms a hinge; and an active material in functional Connection with the joint body, wherein the active material is adapted to receive upon receipt of a Activation signal a change to experience at least one property, with the change the at least one property is effective to the joint body of the to transform the first form into the second form. The device of claim 11, further comprising an outer body overlying the Fugenabdeckkörper arranged and fixed to a selected one of the first surface and the second surface or is attached to both, so that the outer body is effective to the Fugenabdeckkörper visually cover. The device of claim 11, wherein the active material a shape memory alloy, a ferromagnetic shape memory alloy, a shape memory polymer, a magnetorheological elastomer, a piezoceramic or combinations comprising at least one of the foregoing active materials include. Apparatus according to claim 11, wherein the change the at least one property is a change of a shape, a dimension, a phase, a shape orientation, a rigidity or combinations comprising at least one of the foregoing properties. The device of claim 11, wherein the active material a shape memory alloy is and the change the at least one property is a stress-induced superelasticity that is effective to reverse the change of Fugenabdeckkörpers of to admit the first form into the second form. Apparatus according to claim 11, wherein the activation signal a thermal activation signal, an electrical activation signal, a magnetic activation signal, a chemical activation signal, a mechanical load or a combination that at least includes one of the preceding activation signals. The apparatus of claim 11, wherein the first surface is a door panel, a trunk lid, a hood, a window, a tailgate, a Son roof, a sunroof, a center console, a storage compartment or a glove compartment. The device of claim 11, wherein the second surface is a Vehicle body panel, a vehicle roof or dashboard includes. The device of claim 11, wherein the active material Outside firmly between the Fugenabdeckkörper and a third area is appropriate. The device of claim 19, wherein the active material a shape memory alloy wire is and the change the at least one property is a change in a length dimension which is effective to return the Fugenabdeckkörper of the second form in the to transform the first form. Method for covering a joint between a first surface and a second surface, wherein the method comprises: a joint cover between the first surface and the second surface is positioned, wherein the Fugenabdeckkörper comprises an active material, wherein the active material is adapted to receive an activation signal between a first stiffness and a second stiffness The change is a movement of a selected one of the first surface and the second surface or both, so that the joint cover body with the movement of the surface deformed to maintain the cover of the joint; the active material with the activation signal is activated to yourself from the first stiffness to the second stiffness; and a selected from the first surface and the second surface or both moved from a first position to a second position will be.